This invention relates to the treatment of the mammalian eye; human and animal. It also relates to optical onlay lamellar keratoplasty that changes the topography and topolomy of the anterior corneal surface, which results in the alteration of the refracting power of the cornea. It specifically relates to improvements in the epikeratophakia process.
Epikeratophakia are surgically performed on patients unable to have their vision problems corrected by penetrating keratoplasty, corrective lenses, or for various medical reasons. The ocular conditions that can be corrected by epikeratophakia consist of keratophakia, keratomileusis, aphakia, keratoconus and myopia. U.S. Pat. No. 4,662,881 is representative of prior art epikeratophakia.
More specifically, the prior art epikeratophakia process or surgery is generally performed in the following steps: (1) the appropriate corneal topography to correct the manifested problem is identified by reference to specific location; (2) lyophilized donor tissues are obtained and made readily available; such donor tissue consists of stroma lacking endothelium and epithelium appropriately shaped by a specific computer program; (3) perform annular keratectomy by trephination some distance away from the axis of the optical corneal center; such procedure is to remove optical field corneal epithelium, but not stromal tissue, from the patient's eye; (4) rehydrate the computerized shaped cornea; (5) place rehydrated cornea into correct position within the keratectomy site; (6) suture such donor tissue to patient's cornea at the keratectomy site; (7) treat the surgical site with antibiotics and anti-inflammatory agents. The aforesaid prior art procedure excites the process whereby keratocytes migrate from the patient's stroma into the donor tissue with reepithelialization occurring over the transplanted tissue within days.
There are major disadvantages to the prior art epikeratophakia. The major disadvantage is suturing the donor corneal material to the patient's cornea. As others have expressed, this is a difficult operation which requires great skill and precision. In addition, the appropriate corneal topography to correct the vision problem is distorted by the suturing procedures. In short, suturing results in diminished visual benefits to the patient and represents a risk to the patient.
It is also well known that extensive inflammation usually occurs after suturing requiring careful post-operative monitoring and treatment for the inflammation.
Suturing of the donor corneal material to the patient's cornea is very time consuming, e.g., at least one hour per eye; therefore, the patient is under the surgical procedure for a relatively long time and invariably ocular infections result because of the length of time required for suturing.
Severe or uncontrolled blepharitis, dry eyes or lagophthalmos are contraindicated for the prior art procedures currently employed for epikeratophakia surgery.